Oswego Township occupies the 6 mile square plus additional land to the South of the Fox River in northeast corner of Kendall County, Illinois.

It is located at 41.693183 N, -88.335179 W. It has 103.217 km2. (39.852316 square miles) of land and 1.675 km2. (0.6469 square miles) covered by water. Its population in the 2000 Census was 28,417. It has 10,237 housing units.

U.S. Route 34 runs east to west through the township. Aurora, Plainfield, and the Village of Oswego cover much of the township.

Oswego Township was named after the Village of Oswego, which was in turn named after the largest city in the home state of many of the area's first settlers. Oswego is an Iroquois Indian word meaning place of the flowing out or mouth of the stream. Oswego, New York, Oswego Township's namesake sits at the mouth of the Oswego River, while Oswego, Illinois sits at the mouth of Waubonsie Creek.